Many existing animal models and traditional cell culture based models do not adequately reflect pathogen-host interactions or even support the growth of human enteric pathogens. The Wells lab has developed a human intestinal organoid (HIO) system, where HIOs are derived from the directed differentiation of human pluripotent stem cells (hPSCs). This pioneering approach allows for in vitro studies of human enteric pathogens, both viral and bacterial. Importantly, we have been instrumental in disseminating this technology to the global research community. We have trained numerous investigators, at our institution and around the world in the use of this technology. For example in studying bacterial and virus-host interaction (3) the lead author was trained in my lab and brought the HIO technology back to Mary Estes lab at Baylor. We have also hosted weeklong HIO training sessions for trainees from the labs of Dr. Jim Goldenring (Vanderbilt), Dr. Calvin Kuo (Stanford), Dr. Martin Martin (UCLA). In this application the human organoid core will fill current gaps in enteric disease research by developing new systems to identify molecular pathways involved in pathogenesis of enteric agents. In addition, we will carry on our tradition of providing human gastrointestinal tissues, training, and support to researchers affiliated with this proposal, and to all other investigators in the field. Human PSCs can differentiate into all cell and tissue types of the body, and can therefore be used to generate tissues that can be used to study a plethora of disease processes affecting different organ systems. Moreover, with the advent of induced pluripotent stem cell technology, pluripotent stem cell lines can be generated from any patient, allowing for patient-specific disease modeling and therapies. Because of the enormous potential of PSCs, Cincinnati Children's Hospital Medical Center (CCHMC) supported the establishment of the human Pluripotent Stem Cell Facility (PSCF) (https://research.cchmc.org/stemcell/), established by Dr. Wells in 2007 and co-directed by Dr. Mayhew. This was one of the first human pluripotent stem cell cores in the country and has been used as a model for cores at other institutions such as Cleveland Clinic and Case Western (http://pscf.case.edu/). In aim 1 the core will generate and provide iPSCs as well as training to the U19 investigators. We have trained many labs around the world in HIO technology and should we become part of a U19 consortium, CCHMC had committed to fully support the training of personnel from all participating NAMSED institutions (see letter from Dr. Arnold Strauss). In aim 2 we will generate and provide genetically modified PSC lines and gastrointestinal organoids for mechanistic studies of enteric pathogens (Table 1) proposed in the 3 projects. These will be used to identify pathogen targeted cell types and molecular pathways that function in specific cell types during pathogenesis.